Nico Minoru (briefly known as Sister Grimm), is a fictionalcomic book character in the Marvel Comics award-winning series, Runaways. Created in 2003 by writer Brian K. Vaughan and artist Adrian Alphona, the character first debuted in Runaways vol. 1 #1 (July 2003) with most of the other main characters. Like every member of the original Runaways, Nico is the daughter of the super-powered villains calling themselves "the Pride"; in her case, she is the daughter of dark wizards. Upon finding out, Nico runs away with the rest of the runaways but later discovers that she inherited her parents' magical aptitude. Whenever Nico bleeds, a powerful staff emerges from her chest, allowing Nico to bend magic.

By the second series, Nico is the de facto leader of her unofficial and nameless superhero team, making her one of the few Japanese-American superhero team leaders. Nico's trademark is her elaborate and ornate Gothic wardrobe. Nico is a sorceress like her parents and great-grandmother before her and can cast nearly any spell imaginable with her Staff. Nico uses her talents to make up for her parents' villainous actions and to prevent anyone from assuming the Pride's place at the top of Los Angelesorganized crime.

In Brian K. Vaughan's original pitch for the series, Nico was called Rachel Messina. Her parents were still magicians, but posed as wealthy antique dealers; this cover story was ultimately used for Gert's time travelling parents. Nico's source of power wasn't originally going to be her mother's Staff, but Robert Minoru's spellbook.

Every year, Nico's parents join five other couples in a charity event; one year, Nico and the other kids spy on their parents. Nico is shocked to discover her father speaking an enchantment, and after witnessing the murder of an innocent girl by their parents ("the Pride"), Nico joins the others in their massive ransack to run away from their parents. While on the run, Nico encounters her parents. Her mother, wielding a large staff with a ball at the end ("the Staff of One"), reveals that she and Nico's father are dark wizards; she then attempts to jam the Staff into Nico's chest. Nico's body, curiously, absorbs it. After she is later cut by Dale Yorkes' Samurai battle-axe, the Staff re-emerges from her chest, which prompts Nico to use the phrase "Freeze", and freeze Stacey Yorkes. Nico is revealed to be a witch, and the Staff only emerges when she bleeds. Sometime after running off, Nico takes on the name Sister Grimm to escape the name her parents gave her, but drops it after a while. After team leader Alex outs himself as the mole and is defeated along with the Pride, Nico is accepted as the groups' leader.